Flexible fins for swimmers



C. A. DRUMMOND FLEXIBLE FINS FOR SWIMMERS Oct. 29, 1968 2 Sheets-Sheet 1 Filed Jan. 16, 1967 FIG.

FIG. 2.

INVENTOR. CHARLES A DRUMMOND W PATENT ATTORNEY Oct. 29, 1968 c. A. DRUMMOND 3,407,419

' FLEXIBLE PINS FOR SWIMMERS Y I Filed Jan. 16, 1967 2 Sheets- Sheet 2 FIG. 5.

IN VENTOR. CHARL E5 A. DRUMMO/VD B fl PATENT ATTORNEY United States Patent 3,407,419 FLEXIBLE FINS FOR SWIMMERS Charles A. Drummond, 100 Harbor Blvd., #17,

' Belmont, Calif. 94002 Filed Jan. 16, 1967, Ser. No. 609,565 6 Claims. (Cl. 9-307) ABSTRACT OF THE DISCLOSURE Hinged fins oscillate about a hinge tube which is secured to the forearm of the swimmer. On the down stroke, the fins are projected by the force of movement through the water to horizontal, co-planar position and create a maximum drag through the water. On the up stroke, the fins fold together and create minimum resistance to movement. The device is constructed to limit upward movement of the fins to horizontal'position and to prevent rotation of the fins relative to the hinge tube. Reinforcements may be provided in the fins to prevent bending.

This invention relates to new and improved flexible fins for swimmers. A hinge pin, which may be in the form of a plugged tube, is fastened to the top of the forearm of the swimmer and projects outward beyond the end of the hand. The tube may be provided with a handle to be gripped by the fist of the user. A pair of fins is hinged to the outer end of the tube. On the up stroke the fins fold around the hinge to a minimum resistance position in side-by-side relationship. On the down stroke, the force of the water pivots the fins outward to a protected or coplanar position which accomplishes maximum resistance.

Accordingly, a principal purpose of the present invention is to provide flexible fins which automatically assume a position of maximum drag on the down stroke of the swimmers arm and a position of minimum resistance on the up stroke, thereby conserving energy.

Another feature of the invention is the fact that the hinge pin is fastened to and becomes an outward extension of the arm of the swimmer and thus the use of the device does not involve any material variation from a normal swimming stroke. At the same time, by reason of the fact that the fins are displaced outwardly of the ends of the arm, an augmented leverage is accomplished which permits greater speed.

A further feature of the invention is the fact that the fins are hollow, providing additional buoyancy.

A still further feature of the invention is the provision of abutting edges of the two fins when in projected position which prevent the fins from folding upward to sideby-side relationship and thu limit the upward movement of the fins to a position of maximum effectiveness. At the same time, means is provided on the tubular hinge to prevent rotation of the fins beyond the foregoing described position.

A still further feature of the invention is the simplicity of the construction of the fins and their integral means for hinged connection to the tube.

Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings in which similar characters of reference represent corresponding parts in each of the several views.

In the drawings:

FIG. 1 is a perspective view showing the device installed on the arm of a swimmer and showing the fins in projected position in full lines and in retracted position in dotted lines.

FIG. 2 is an enlarged sectional view taken substantially along the line 22 of FIG. 1.

3,407,419 Patented Oct. 29, 1968 FIG. 3 is a top plan of the forward portion of the device.

FIG. 4 is an end elevation thereof.

FIG. 5 is a bottom plan.

FIG. 6 is a fragmentary perspective view of a portion of a fin.

The present invention is intended for use on the arms of a swimmer. For such purpose there .is provided a hollow plastic tubular portion 11 which is formed fiattened at one end 12 and pierced by two slits 13 for a strap 14 which fits around the forearm of the user immediately below the elbow with the tube 11 extending beyond the ends of the arm a considerable distance. At about the midpoint of tube 11 is a handle member 16 consisting of a collar 17 which fits around the outside of tube 11, downward extending sides 18 and a hand grip 19. Thus the grip 19 may be grasped in the fist of the user for more effectively securing the device on the arm of the wearer. Tube 11 extends beyond the handle portion 16 in a hinge portion 21 which is plugged by an end plug 22 at the front end.

A pair of fins 23 is hinged around the tube portion 21, the fins 23 preferably being of a molded hollow plastic and susbtantially identical in shape so that a single mold is required for the two fins. The fins 23 are trapezoidal in plan, with the shorter base innermost. In the preferred form best shown in FIGS. 3 and 5, each fin 23 is formed with three collar segments 24a, 24b, 24c which fit around tube portion 21, the collar portions 24 being spaced apart a distance about equal to their width so that the collar portions of the two fins interfit in the manner of a leaf hinge, the tube portion 21 functioning as a hinge pin.

To make the fins 23 more rigid and also buoyant, hollow reinforcing ribs 26 are formed on the top surface, said ribs 26 being of maximum width and thickness at the center and tapering both in thickness and in width outwardly to the outer edge of fins 23. As best shown in FIG. 2, the ribs have flat tops 27 and downward slanted side edges 28 which intersect and terminate in a bottom edge 29. Thus a hollow 31 is formed within the ribs 26 to provide buoyancy. The inner edges 32 of the ribs abut (see FIG. 3) and thus limit upward movement of the fins so that at their maximum extension they are coplaner. To prevent rotation of the fins relative to tubular portion 21, inward projections 36, 37 are formed on handle collar 17 and plug 22, respectively, and complementary notches 38, 39 are formed on the outer corners of the fins. Hence when the fins are in projected position, they engage projections 36, 37 and are thus prevented from turning beyond the position of maximum extension. Handle 16 holds the fins apart a short distance in retracted position in proper relationship for the downstroke. Thus the slightly spread position insures that the fins pivot properlythe left fin of FIG. 4 turning clockwise and the right fin counterclockwise.

Fins 23 are made up of a top member 41 on the upper surface of which the ribs 26 are formed and a bottom 42. The members 41 and 42 are bonded together around their peripheries, as by cement, heat bonding or similar means.

In use, the tube 11 is strapped to the top of the forearm of the user by strap 14 as best shown in FIG. 1. The fingers are inserted through the handle portion 16 and grip the grip 19. Thus, in effect, the device becomes an extension of the arm of the swimmer. On the up stroke, the force of the water on the top of the fins 23 causes them to pivot downwardly, the collar sections 24a, 24b, 24c turning around the tubular hinge 21 until the dotted line position of FIG. 1 is assumed. With the fins 23 thus in side-by-side position, the resistance to movement through the water on the up stroke is minimized and the effort required to lift the fins through the water, is reforce of the water against the undersidesflofthe fins causes them to fold outward to full line position, andthe abutting edges 32 of the reinforcing meet and iimit further outward]movement of the finsl Similarly,

3Q prevent turning 'of theffin's relative to 'the handle. In this position, a maximum resistanee to rnc'iveme'nt through the water is "provided and'hence 1 the effectiveness of the swimming "stroke is greatly increased. The fins oscillate freely between'retractedand projectedposition as the swimmeralternately moves his forearm through the up stroke and down stroke movement.

What is claimed is: i g

1. A device of the character described comprising a longitudinally extending hinge pin member, first means for" securing said member to the forearm of the user, a pair of fins each having collar sections fitting around said hinge pin member for pivotal movement around said hinge pin member between a retracted position with said fins substantially side-by-side and a projected, substantially coplanar, position, and second means limiting movement of said fins away from retracted position beyond projected position, said hinge pin member having a thin, elongated portion extending a distance rcarwardly beyond the inner edges of said fins about as far as the width of said fin-s,

the PIQJBCUOIIS 36, 37 nterfittingagain'stjthe notche 38,

saidflfi'fstl fiieans located onsaid portion and rearwardof a dvfi 1 2f A'dev'ice according to claim liriwhich saidfirst means "comprises a strapsecured to the proximal'end of said hinge pinmemb'eri 3. A device' according a; claim 2 in which said means also comprises a grip depending rom said hinge pin member spaced i'earwardly from the inner edges of said 4. A device according to claim I which further cornprisesreinfo rcing ribs'exteiiding alongsaid fins, the inner;

in projected position. v y g I sfA jdevice according" to claim which said ribs are;

edges ot ribs of opposite fins abnttin'g' when said this are I hollow'andwater-tight 6 A device acoordingto claim 4 in which s 'aid this in plan are trapezoidal."

W References Cited UNITED STATES PATENTS 1,626,163 4/1927 Smith 9 303 2,343,468 1 3/1944 Messinger s .;9304 3,097,375 18/1963 Griffith "9-307 FOREIGN PATENTS 992,948 5/1965 Great Britain.-

MILTON BUCHLER, Primary Examiner.

J. PITTENGER, Assistant Examiner. 

